An extreme ultraviolet (EUV) light source based on a discharge within a wide-angle buffer gas heat pipe has been disclosed by McGeoch [1]. In addition, other wide-angle heat pipe EUV source designs have been disclosed [2,3,4] in all of which the heat pipe structures must be thin in order to transmit the maximum amount of EUV light. Intense heat of up to several kW has to be applied at the smallest inside radius of the conical or disc-shaped heat pipe structures, to evaporate lithium from a location as close as possible to where it is needed for the discharge, yet allow its out-board re-condensation at as small a radius as possible. Very thin and compact heater structures are therefore necessary. In prior work on metal vapor heat pipes in which the constraints are not so demanding, the source of heat has variously been one of: induction heating of the outside of a cylinder via a field coil [5,6]; resistance wire in an insulator [1]; electron beams; or a flame [7]. As the geometry moves from a cylinder [5] to a disc [7] to three-dimensional [1], the heating problem becomes more acute. Although one could consider laser heating, it has the disadvantages of requiring a complex optical distribution system, and high cost.